The flow of blood within extracorporeal membrane oxygenator (ECMO) devices hasbeen identified as one mediating factor in thrombus deposition. Thus, the determination of the flow field occurring within the device is of paramount importance with respect to design refinement. Computational fluid dynamics (CFD) offers an alternative to traditional flow visualization techniques, which for complicated geometries and opaque working fluids such as blood, prove costly and time consuming. A 2-D model of blood flow within an ECMO device has been developed and was used to predict areas of thrombus deposition found in clinically used devices. It is the objective of this proposal to extend this analysis to 3-D so as to more accurately account for those regions where 3-D effects are clearly important. This work will also form the foundation for the addition of a mass transfer model and subsequent design optimization.